Production of viscose



Patented lian. l0, 1928,

vsierras Fill-ITE MEMIETER, mh hwwlll'lhlhfllll', lll-Ehflflddll'llriaonuurmit or viscose.,

uit man-ing, Vamerita-non nea maan et, itat, anni m. rattan una nurinary .nay it, raar,

lily invention refers to the art ot melting artihcial :hhres such asrartilicial sillr and more particularly to the production ol viscose toruse in this manutacture.. lt is an ll ohject ot the present invention toimprove the preparation ot the viscose with a view to rendering theprocess more ecient and 'to obtaining a product ot higher quality thanwas hitherto possible.

Jts is well linown to those slrilled in the art, when producing viscose,the Xanthate required theretor is as a rule prepared in such manner thatthe aged allrali cellulose is saturated with carhon disultide in themirrlll ing drum, the carhon disultide and volatile carhon disulhdecompounds in excess heing suclred ott trom the drum at the end ont theoperation, whereupon the ranthate olotained is .dissolved in a separatestirring apparatus 'im loy means ot dilute caustic soda to lorm aviscose-oil the required concentration.

Experience has shown that in the :ranthate thus produced, -which vleavesthe mining drum in the lorm ot smaller or larger tl nodules, there areenclosed, hesides supersa-tu'rated cellulose particles, also such particles which are only impertectly saturated with cartoon disulhde.lnasmuch as the carhon disulhde in excess had hetore heen tu removed,these particles will remain insolu-v hle during the dissolvingtreatment, which fitollows the saturation process, and will inlluencevery untavorahly the filtration y processv hy clogging lthe lters. 0nthe 'at other hand those particles of cellulose enclosed within thecrumbs and nodules ot the'ranthate during the suclring oil, which carrycarhon disullide in excess, when underf going dissolving treatment, willgive oil this tu carhon disulde to the viscose solution which ,is alsoundesirahle. f

ln the process according to the present invention these drawbacks areoliviated hy slowly dissolving the Xanthate in the dilute tl causticsoda under permanent vigorous lmeading in the presence of the carbon'disul-g hole which is still uncomhined, hetore removing the carhondisulhde in errcess. lt the process is carried out in this manner, thereis hrst termed a tough paste which pertu mits the carhon disuldein'ercess which is liloerated trom the cellulose particles hy thevigorous lrneading and lriction to enter those cellulose particles whichwere not tully saturated and to completely dissolve them, at @loviouslyhy thus'proceeding all the cellulose particles are subjected vto theaction ot the carbon disulidde.v @nly alter continued hneading and alterthe desired degree ol dilution has heen attained, the residue ol tu treecartoon disulhde and volatile compounds, which may still he present, issuclred oliin trom the viscose under permanent stirring and a viscosesolution is ohtained which is suhstantially -tree ol non-dissolvedcellulose t5 and ot `non-combined vcarhon disulhde and thereforeconstitutes a decidedv improvement upon similar 'productshithertoohtained..

ln carrying the novel method into praetice l preter using a stronglrneading ma- 'lo chine permitting sucking-od in vacuo and in which theentire process ot thionat'ion, dissolving and suction can loe carriedthrough.

l wish itto he understood that l do not desire to he limited to theenact details ot 'la operation and construction above described, asobvious modications will occur to a person skilled in the art. v

The process ot producing viscose solution 30 comprising' saturatingvnurtured alkali-cellulose withcarhon disulfide, lmeading the Xanthatethus olotained with caustic soda solution -and water in the presence ofan excess of carhon disulde and other volatile coin- B5 pounds whichhave not combined with the cellulose and then only, freeing the viscosesolution thus obtained from the volatile constituents.

In testimony whereof I aix my signature.,

Farra nmmrna,

